Conventional devices such as keyboard musical instruments are known in which an acoustic transducer operates in accordance with an audio signal to thereby vibrate a vibrated body, so that the vibrated body generates sounds. For instance, in a keyboard musical instrument, the acoustic transducer is fixed to a back post via a support member, and a movable unit is connected to a soundboard that functions as the vibrated body to be vibrated. The movable unit is configured to vibrate when an electric current based on the audio signal is supplied to a coil. The vibration of the movable unit is transmitted to the soundboard, so that the soundboard is vibrated to thereby generate sounds.
The following Patent Literature 1 describes an installation structure for the acoustic transducer in the keyboard musical instrument. In the disclosed structure, the movable unit in the form of a rod-like hammer is electromagnetically coupled to a magnetic-path forming portion having a magnet, a core, and so on. When an electric current is supplied to the coil, the movable unit reciprocates in its axial direction, so that the movable unit vibrates. The movable unit is fixedly bonded at its distal end portion to a flange fixed to the soundboard.